Bug 1933927

Summary:	ssh login with pam_faillock doesn't display "Account temporarily locked due to %d failed logins".
Product:	Red Hat Enterprise Linux 8	Reporter:	Muneaki Sugaya <msugaya>
Component:	openssh	Assignee:	Jakub Jelen <jjelen>
Status:	CLOSED NOTABUG	QA Contact:	BaseOS QE Security Team <qe-baseos-security>
Severity:	medium	Docs Contact:
Priority:	unspecified
Version:	8.3
Target Milestone:	rc
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Hardware:	Unspecified
OS:	Linux
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Last Closed:	2021-03-02 12:23:28 UTC	Type:	Bug
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Comment 1 Jakub Jelen 2021-03-02 12:23:28 UTC

There is no API in the SSH protocol to give more information about failed password authentication attempts when using normal password authentication:

https://tools.ietf.org/html/rfc4252#section-8

https://tools.ietf.org/html/rfc4252#section-5.1

The PAM messages should be visible in case the ChallengeResponseAuthentication is used (normal PasswordAuthentication should be disabled in that case). This allows the PAM to communicate additional messages with the client. It is described in the following RFC:

https://tools.ietf.org/html/rfc4256

How to test it:

 * Modify sshd_config to have

    ChallengeResponseAuthentication yes
    PasswordAuthentication no

 * Restart sshd

    systemctl restart sshd

 * Try to connect with the test user:

    # ssh testuser@localhost
    The account is locked due to 3 failed logins.
    (9 minutes left to unlock)
    Password: